EP3098072A2 - Method for the production of laminates - Google Patents

Abstract

Shown and described is a process for producing a laminate comprising at least one carrier layer and a further layer comprising the steps a. Making an impregnate by soaking a base paper with a composition containing a synthetic resin, b. Providing a layer comprising a carrier layer and an impregnate by applying the impregnate to the carrier layer, c. Hot pressing the layer provided, wherein the curing agent releases at least one acid by hydrolysis during hot pressing and the carrier layer has a water vapor transmission resistance of at least 250. The method described is particularly suitable for producing coated compact plates.

Description

The present invention relates to a process for producing laminates and to the use of an acid-releasing curing agent for synthetic resins for the production of such laminates. The invention further relates to laminates produced by this method.

If laminate is mentioned here or elsewhere, this may in particular mean a material which consists of two or more layers glued together in a flat manner. These layers can consist of the same or different materials.

Laminates are used in everyday life in many places. Very well known is the use of laminates for floors. But laminates are also used in furniture production. In addition, laminates can be used in the manufacture of interior and / or exterior furnishings. The reason for the variety of possible uses for laminates lies in the high flexibility of the composition of laminates. Therefore, the properties of laminates can be tailored to the respective application. Laminates offer a great deal of freedom in terms of their optical design. The resistance, in particular the scratch resistance, can be influenced in a targeted manner by the use of suitable materials in the laminate production.

Typically, laminates consist of a carrier layer to which decorative paper is applied. The decorative paper can be printed, which opens up the optical design possibilities of laminates. The printed surface of the decorative paper significantly determines the appearance of the laminate.

For example, can be imitated by a suitable imprint on the decorative paper, a wooden surface.

In addition to the usual, already mentioned components of the carrier layer and the decor paper laminates may contain other ingredients. Between the carrier layer and the decor paper, one or more base papers may be included. As base papers often so-called underlays are used. Underlays can act as a barrier between the support layer and the decorative paper and prevent chemical interference between the resin components of the support layer and decorative paper. Base papers can also be used to achieve other effects. For example, the use of a base paper can produce desirable optical effects. The use of base papers can also be favorable for procedural reasons.

In addition, laminates may also contain so-called overlays. Overlays are usually substantially transparent papers with a high resin uptake capacity. Overlays can be used to protect the printed image of printed decor papers. They can also be used to improve abrasion resistance. Usually, overlays are applied to the laminate as the topmost layer. A special case of the overlays are so-called liquid overlays. These may consist of a resin, for example an aminoplast resin, which may contain particles, in particular abrasive particles. Liquid overlays are usually applied to the laminate as the topmost layer.

Another important ingredient of laminates are resins. In particular, synthetic resins have proven to be particularly practical in connection with laminate production. Usually, a laminate contains at least one synthetic resin. However, a laminate may also contain several, in particular different, synthetic resins. Synthetic resins are usually used in laminates to bond the individual layers together. For example, you can thicker layers of a laminate contain a first synthetic resin. By bonding a thicker layer already containing a first synthetic resin to at least one other layer, a laminate may contain more than one synthetic resin by using another synthetic resin other than the first synthetic resin.

Synthetic resins are known to those skilled in principle. Synthetic resins are for example in Rompps Chemie-Lexikon, 7th edition, Frankh'sche Verlagshandlung Stuttgart, 1973, page 1893 described. A group of synthetic resins, which is particularly important for laminates, are condensate resins. These harden by condensation reactions, in which water is often split off. Condensate resins include, for example, phenol-formaldehyde resins and aminoplast resins.

The curing of synthetic resins, in particular condensate, can be done for example by addition of acidic catalysts. Normally, organic acids such as citric acid and maleic acid, inorganic acids such as sulfuric acid and phosphoric acid, salts which react acid in water such as aluminum chloride and aluminum nitrate (also referred to as acid salts), salts obtained by reaction with components of the synthetic resin, preferably with formaldehyde to generate an acid (also referred to as acid-generating salts) such as ammonium phosphate, ammonium sulfate and ammonium chloride, and mixtures of the aforementioned substances are used.

To produce laminates, it is possible to start from a carrier layer onto which the further layers are applied. In this way, first a stratification is obtained. A stratification can consist of two or more layers. The layers may be the same or different. Neighboring layers can in particular have direct contact in a stratification. The existing edges of the individual layers can be aligned in a layering in a specific manner, for example parallel to one another. Usually, the components of a stratification are not yet together pressed. In the further process, the layering can then be adhesively bonded under pressure and / or under the influence of temperature to form a laminate.

The layers which are to become part of the layering can be soaked with a composition containing a synthetic resin before being applied to the support layer. Such impregnated layers can also be referred to as impregnates in particular. Preferably, impregnates of papers such as overlays, underlays and / or decorative papers are produced by impregnation with a composition containing a synthetic resin.

As carrier layer different materials come into question. Often wood-based materials are used. Examples of wood-based materials are chipboard, wood fiber boards and oriented strand boards (OSB boards). However, other materials such as materials containing a plastic and / or a synthetic resin may be used.

Intensive research has been carried out in the area of synthetic resins, which are important for the production of laminates.

The WO 2002/068178 A2 describes a method for bonding laminates with an aminoplast resin in which the aminoplast resin and the hardener containing an acid, an acidic salt and / or an acid-generating salt are applied separately to the adherends.

The WO 2005/030895 A1 describes binder systems which, besides aminoplast resins and N-functionalized copolymers, also contain at least one acid, an acid salt and / or an acid-generating salt.

Furthermore, in the EP 427 058 A2 a process for Rollenheißkaschierung of wood materials using an aqueous hardener mixture for the curing of aminoplast resins described.

The DE 10 2004 034 528 A1 describes the use of melamine resin films for coating three-dimensionally structured surfaces, in particular wood-based materials.

A disadvantage of the hardener compositions listed in the prior art, on the one hand, that the curing of the resin is difficult to control when using acids as a hardener, since the curing can begin even with the addition of the acid. The same applies to the use of acid salts, in which the curing can also begin with the addition of the acidic salts. The disadvantage of the acid-generating salts is that these salts usually require free formaldehyde, for example, to form acid with the ammonium salts. In this respect, often more formaldehyde than is needed for the curing of the resin must be added. Normally, however, this formaldehyde is not permanently bonded and may be slowly released after completion of the manufacturing process, as well as other free formaldehyde from the condensate resin. However, the subsequent release of formaldehyde is undesirable. Efforts to reduce the free formaldehyde content using the prior art hardener compositions have generally resulted in retarded cure of the resin as well as lower bond strengths of the bonded layers, which may affect the mechanical properties of the laminates.

The methods listed in the prior art prove to be particularly disadvantageous for those carrier layers which can dissipate and / or absorb water vapor poorly. For support layers which can poorly dissipate and / or absorb water vapor, normally press times of 2.5 to 3.5 minutes must be maintained by prior art pressing techniques to obtain smooth surfaces of the laminates. In contrast, the resin can typically be cured faster, for example, after only 20 seconds. Shorter press times lead to a blistering of the Surface of the laminates. This is probably due to the fact that the water contained in the resin evaporates and can not escape. This is usually counteracted by the above-mentioned, longer pressing times, with a longer cycle time and thus a lower productivity and thus a lower cost-effectiveness is accepted.

On the basis of the above-described prior art, an object of the invention was to provide a method which makes it possible to produce laminates with shorter pressing times than is required in the prior art.

This object is achieved by a method according to claim 1 and a laminate according to claim 22 and a use according to claim 23.

Advantageous embodiments of the invention are described in the dependent claims and are explained below as the general inventive concept in detail.

1. a. Herstellen eines Imprägnats durch Tränken eines Basispapiers mit einer Zusammensetzung, die ein Kunstharz enthält,
2. b. Bereitstellen einer Schichtung umfassend eine Trägerschicht und ein Imprägnat durch Aufbringen des Imprägnats auf die Trägerschicht, und
3. c. Heißpressen der bereitgestellten Schichtung,

wobei ein Härter für das Kunstharz verwendet wird, der beim Heißpressen durch Hydrolyse mindestens eine Säure freisetzt.The process according to the invention for the production of laminates comprising at least one carrier layer and a further layer, comprising:

1. a. Making an impregnate by soaking a base paper with a composition containing a synthetic resin,
2. b. Providing a lamination comprising a carrier layer and an impregnate by applying the impregnate to the carrier layer, and
3. c. Hot pressing of the provided stratification,

wherein a curing agent is used for the synthetic resin, which releases at least one acid during the hot pressing by hydrolysis.

In particular, the water vapor diffusion resistance number (μ number) can be used to classify materials. The water vapor resistance coefficient can be determined by testing in accordance with DIN EN ISO 12572, in particular according to DIN EN ISO 12572: 2001-09. She indicates to which factor the material in question is closer to water vapor than an equally thick, static layer of air. The larger the μ-number, the more vapor-tight is a material. Typically, the water vapor resistance coefficient of a fabric in the dry state is determined. For example, a chipboard in the dry state has a water vapor diffusion resistance number of 50. On the other hand, an OSB board normally has a water vapor resistance of 200 when dry.

1. a. Herstellen eines Imprägnats durch Tränken eines Basispapiers mit einer Zusammensetzung, die ein Kunstharz enthält,
2. b. Bereitstellen einer Schichtung umfassend eine Trägerschicht und ein Imprägnat durch Aufbringen des Imprägnats auf die Trägerschicht, und
3. c. Heißpressen der bereitgestellten Schichtung,

wobei ein Härter für das Kunstharz verwendet wird, der beim Heißpressen durch Hydrolyse mindestens eine Säure freisetzt, und die Trägerschicht eine Wasserdampfdiffusionswiderstandszahl gemäß Prüfung nach DIN EN ISO 12572 von mindestens 250 aufweist.The process according to the invention for the production of laminates comprising at least one carrier layer and a further layer, comprising:

1. a. Making an impregnate by soaking a base paper with a composition containing a synthetic resin,
2. b. Providing a lamination comprising a carrier layer and an impregnate by applying the impregnate to the carrier layer, and
3. c. Hot pressing of the provided stratification,

wherein a curing agent is used for the synthetic resin, which releases at least one acid by hydrolysis during hot pressing, and the carrier layer has a water vapor diffusion resistance coefficient according to the test according to DIN EN ISO 12572 of at least 250.

Surprisingly, it was found that in the process according to the invention by the use of a curing agent for the synthetic resin which releases at least one acid by hot pressing during the hot pressing, the pressing times can be considerably shortened compared with the pressing times customary in the prior art. Without wishing to be bound by any scientific theory, this surprising effect seems to be explained by the fact that the acid-releasing hardener binds the water vapor produced during hot pressing.

As explained at the outset, synthetic resins are generally known to the person skilled in the art. Synthetic resins are for example in Rompps Chemie-Lexikon, 7th Edition, Frankh'sche Verlagshandlung Stuttgart, 1973, page 1893 described. A special for laminates important group of synthetic resins are condensate resins. These harden by condensation reactions, in which often water is split off. The condensate resins include, for example, phenol-formaldehyde resins.

Phenol-formaldehyde resins can be obtained by condensation of phenol or a phenol derivative with a carbonyl compound. Common starting materials for phenol-formaldehyde resins are, for example, phenol and formaldehyde (as carbonyl compound). Phenol-formaldehyde resins can be obtained in a two-step process. In this case, a precondensation of the phenol derivative with the carbonyl compound can take place in a first step. In a second step, often referred to as curing, the phenol-formaldehyde resin can then be crosslinked throughout.

Also, the condensate resins include aminoplast resins. Aminoplast resins are known to the person skilled in the art and are described, for example, in US Pat. Ullmanns Enzyklopadie der technischen Chemie ", 4th Edition, Volume 7, p. 403ff , described. Aminoplast resins can be obtained by condensing an amino, imino or amide group-containing component with a carbonyl compound. Common starting materials for aminoplast resins are, for example, urea and / or melamine (as the amino-containing component) and formaldehyde (as the carbonyl compound). In the latter case, the amino-containing component is usually precondensed in a first step with the carbonyl compound to a certain degree. Depending on whether in the first step, for example, only melamine or only urea is used as the amino-containing component, one obtains a so-called melamine resin or a urea resin. Such melamine and / or urea resins may in particular form the main constituents of aminoplast resins. In a second step, often referred to as curing, the aminoplast resin can then be crosslinked throughout. Resins formed from urea and formaldehyde are also referred to as urea-formaldehyde resins. Resins formed from melamine and formaldehyde are referred to as melamine-formaldehyde resin.

Whenever aminoplast resins are mentioned here or elsewhere, they are meant to include aminoplast resin compositions. Aminoplast resins and / or aminoplast resin compositions may also contain water.

In the method according to the invention, a stratification is provided. Preferably, a lamination consists of two or more layers. The layers can be the same in particular. Alternatively, the layers may be different from each other. Advantageously, adjacent layers in a lay-up have direct contact. The existing edges of the individual layers can, in particular, be aligned in a layering in a specific manner, for example parallel to one another. Preferably, the components of a stratification are not yet pressed together.

The layers which are to become part of the layering can be soaked with a composition containing a synthetic resin before being applied to the support layer. Such impregnated layers are also referred to as impregnates. Impregnates are produced, for example, from papers such as overlays, underlays and / or decor papers by impregnation with a composition containing a synthetic resin.

The carrier layer in the process according to the invention has a water vapor diffusion resistance number according to testing according to DIN EN ISO 12572 of at least 250, preferably at least 500, more preferably at least 1000. In the method according to the invention, the carrier layer more preferably has a water vapor diffusion resistance number according to the test according to DIN EN ISO 12572 of at least 2000.

The inventive method is particularly suitable for the production of coated compact disks. In particular, compact plates coated with the method according to the invention can be produced in a two-stage process.

Compact plates usually consist of several soaked with phenol-formaldehyde resin Natronkraftpapieren. These are connected to each other under temperature and / or pressure. As a result, the resin cures and the Natronkraftpapiere stick together. A compact plate can contain up to 20 soda kraft papers. Compact slabs can have a water vapor resistance coefficient according to DIN EN ISO 12572 testing of up to 17,000. Preferably, compact disks have a thickness of 2 mm or more. Compact panels can be defined in accordance with the requirements of DIN EN 438, in particular according to DIN EN 438-4, in particular according to DIN EN 483-4: 2005-04.

Natron kraft papers can consist of up to 100% pulp fibers. Natron kraft papers can have a very high strength. Natron kraft papers can also be referred to as Kraft papers or as core layers.

According to the invention, a hardener for the synthetic resin is used, which releases at least one acid during hot pressing by hydrolysis.

Hydrolysis in the sense of the invention may in particular mean the cleavage of a (bio) chemical compound by reaction with water. In particular, it is possible in this case to formally deliver a hydrogen atom to the one gap piece and the remaining hydroxyl group to the other gap piece.

According to a preferred embodiment of the invention, the release of the acid contributes to the curing of the synthetic resin. This may be the case, in particular, when the synthetic resin can be cured by acid catalysis. This helps to reduce press times.

Advantageously, the curing agent in the process according to the invention releases at least one acid in the presence of water and / or under the action of heat. Especially The hardener preferably releases an acid in the presence of water and under the effect of heat. In this way, it can be specifically controlled under which conditions the hardener releases the at least one acid. This allows a good control over the procedure.

In a preferred embodiment of the process according to the invention, the at least one acid liberated during hot pressing is formed by reaction of the hardener with water vapor. This allows a permanent bond of the resulting water vapor during hot pressing. As a result, blistering on the surface of the laminate is particularly effectively suppressed.

In use experiments it has been found that it is particularly expedient in the process according to the invention if the pressing time during hot pressing is less than 120 seconds. In particular, it has proved to be advantageous if in the process according to the invention the pressing time during hot pressing is less than 110 seconds, preferably less than 100 seconds, more preferably less than 90 seconds. Most preferred is a hot press pressing time of less than 85 seconds. Such pressing times represent an optimal compromise between a product with a smooth, bubble-free surface and a particularly economical implementation of the method.

Suitable temperature ranges for the hot pressing in the process according to the invention are in particular temperatures of 110 ° C to 200 ° C, preferably from 120 ° C to 190 ° C, more preferably from 130 ° C to 180 ° C. The hot pressing in the process of the invention can also be carried out at a temperature of 140 ° C to 170 ° C. At temperatures in these areas, a particularly smooth surface of the laminate is obtained. At lower temperatures, the pressing time may be longer.

For economic and procedural reasons, it has proved to be advantageous if in the process according to the invention in hot pressing a pressing pressure from 1 to 90 bar, preferably from 10 to 80 bar, more preferably from 20 to 70 bar is used. Such pressures ensure a particularly good bonding of the layers of the laminate together. In addition, blistering can be further minimized with such a pressure.

For many applications, it is particularly practical if, in the process according to the invention, the amount of acid-releasing hardener is 0.5 to 30% by weight, preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, even more preferred 1 to 10 wt.%, Based on the total mass of synthetic resin and acid-releasing hardener is. Most preferably, the amount of acid-releasing curing agent in the process of the present invention is from 1 to 5 weight percent, based on the total weight of resin and acid-releasing curing agent. In practical experiments, it has been found that the use of less than 0.5% by weight of the acid-releasing hardener results in surface blister laminates at typical press times in the process of the present invention. The use of more than 30% by weight of the acid-releasing hardener, on the other hand, has proved to be economically unfavorable.

According to a preferred embodiment, the acid released in the process according to the invention has a molecular weight of from 40 g / mol to 500 g / mol, preferably from 40 g / mol to 300 g / mol. An acid in this molecular weight range allows effective curing of the resin.

Advantageously, in the process of the present invention, the at least one acid released by the curing agent is a Brönsted acid having a pKa of less than 8, preferably less than 7, more preferably less than 6. Most preferred is the at least one acid released by the curing agent in the process of the present invention a Brönsted acid with a pKa of 3.5 to 5.5. The release of a Brönsted acid can be controlled particularly well in the process according to the invention. With a pKa of Bronsted acid of 8 or greater, side reactions may occur depending on the resin used.

Advantageously, the acid liberated in the process according to the invention contains or represents a carboxylic acid. Preferably, the liberated carboxylic acid has 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms. According to a further embodiment, the acid released in the process according to the invention contains or consists of a hydroxycarboxylic acid. Preferably, the hydroxycarboxylic acid released has 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms. In a further embodiment, the acid released in the process according to the invention contains or consists of a carboxylic acid and a hydroxycarboxylic acid. According to this embodiment of the process, the carboxylic acid has 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and the hydroxycarboxylic acid 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms.

As the acid-releasing hardener, it is possible in principle to employ in the process according to the invention a wide variety of substances which release an acid. It is expedient, in particular, if a hardener which contains an acid anhydride and / or an ester, preferably a lactone, is used as the acid-releasing hardener. The use of a hardener containing an acid anhydride and / or a lactone makes it possible to suppress the formation of bubbles on the surface of the laminates well at pressing times which are typical in the process according to the invention.

The ester used is preferably a carboxylic acid ester. Preferably, the carboxylic acid ester has 2 to 30 carbon atoms, preferably 2 to 15 carbon atoms. Examples of esters are methyl formate, ethyl acetate, ethyl propanoate, propyl propanoate, propyl benzoate. In particular, activated esters such as phenyl esters may also be used.

In a further preferred embodiment of the method according to the invention, the acid-releasing hardener contains or consists of a lactone. By doing so leaves the bubble formation on the surface of the laminates is very effective in suppressing the pressing times typical in the method according to the invention.

As the lactone, an intramolecular ester of a hydroxycarboxylic acid is preferably used. Preferably, the lactone has 3 to 15 carbon atoms, preferably 3 to 8 carbon atoms.

In a particularly preferred embodiment of the process according to the invention, the lactone is gamma-butyrolactone and / or epsilon-caprolactone. It has been found that the use of gamma-butyrolactone and / or epsilon-caprolactone makes it possible to suppress bubble formation on the surface of the laminate particularly effectively at pressing times which are typical in the method according to the invention.

As the acid anhydride, an organic acid anhydride is advantageously used. Preferably, the acid anhydride has 2 to 15 carbon atoms, more preferably 4 to 10 carbon atoms.

In a further preferred embodiment of the process according to the invention, the acid anhydride which may comprise the acid-releasing hardener is selected from the group consisting of acetic anhydride, maleic anhydride, succinic anhydride and dilactide. In a further embodiment of the process according to the invention, the acid anhydride is a mixture of all or part of the abovementioned anhydrides. In a further embodiment of the process, the acid anhydride is selected from the group consisting of acetic anhydride, succinic anhydride and dilactide and mixtures thereof. It has been found that when using one of the abovementioned anhydrides or mixtures of all or part of the abovementioned anhydrides, bubble formation on the surface of the laminate can be effectively suppressed at pressing times which are typical in the process according to the invention.

The synthetic resin used in the process according to the invention may in particular be an aminoplast resin. Aminoplast resins, when used with an acid-releasing curing agent, give particularly good blistering results on the surface of the laminates. In addition, aminoplast resins have the advantage that they are usually colorless and transparent. This can ensure that the visual impression of the decorative paper used under certain circumstances is not distorted.

Preferably, in the process according to the invention, in step a. soaked base paper before application to the carrier layer in step b. dried. In this case, the base paper in particular to a residual moisture content of 3 to 15%, preferably from 4 to 12%, more preferably dried from 5 to 10%. By residual moisture, the skilled person understands the water content of the paper after drying. Standard methods for determining the residual moisture are known to the person skilled in the art. For example, the residual moisture can be determined with suitable moisture analyzers or gravimetrically.

According to one embodiment of the invention, in step a. of the inventive method used as an impregnated base paper an underlay paper. Underlays can act in particular as a barrier between the carrier layer and the decorative paper and prevent chemical interference between the resin components of the carrier layer and decorative paper. It has been found that by using an underlay particularly uniform surfaces of the laminates can be obtained.

According to a further preferred embodiment, in the method according to the invention in an additional step after step b., In particular between steps b. and c., one or more layers to those in step b. obtained layering applied. As a result, the properties of the laminate, in particular the optical properties, can be influenced in a targeted manner.

In a particularly preferred embodiment, in the method according to the invention in an additional step after step b., In particular between steps b. and c., a decorative paper and / or a cover layer, in particular an overlay paper, applied to the layering. Decorative paper can be used to influence the optical properties of the laminate. The decorative paper can be printed. The printed surface of the decorative paper can significantly determine the appearance of the laminate. For example, can be imitated by a suitable imprint on the decorative paper, a wooden surface.

Examples of a cover layer are overlays or liquid overlays. An overlay is a preferably substantially transparent paper with a high resin absorption capacity. Such an overlay can also be referred to as overlay paper in particular. Overlays can be used in particular to protect the printed image of printed decorative papers. They can also be used, for example, to improve the abrasion resistance. Preferably, an overlay is applied as the uppermost layer on the laminate. Another example of a cover layer is a liquid overlay. Liquid overlays may advantageously consist of a resin, for example an aminoplast resin, which may contain particles, in particular abrasive particles. A liquid overlay is preferably applied to the laminate as the topmost layer. In particular, overlay papers used in the method according to the invention may have a weight per unit area of 15 to 80 g / m ² . The basis weight is also referred to as grammage.

Carrier layers having a thickness of greater than 2 mm, more preferably greater than 3 mm, more preferably greater than 3.5 mm, are preferably used in the method according to the invention.

In a further embodiment of the method according to the invention, the carrier layer comprises or represents a compact plate. Practical experiments have shown that the method according to the invention can effectively suppress blistering on the surface, especially in the case of compact plates. In particular, you can Compact disks coated with the method according to the invention are produced in a two-stage process.

In a further embodiment of the process according to the invention, the carrier layer comprises one or more Natron kraft papers impregnated with a synthetic resin selected from the group consisting of melamine-formaldehyde resin, urea-formaldehyde resin, phenol-formaldehyde resin and mixtures thereof.

In addition to the main constituents phenolic resin and / or aminoplast resin, the composition containing a synthetic resin used in the process according to the invention may also contain further constituents, such as wetting agents, release agents and / or emulsions of crosslinkable polymers, such as e.g. Acrylic polymers included. It is also conceivable to add to the composition comprising a synthetic resin hardener, for example the acid-releasing hardener and / or a further hardener specially designed for the synthetic resin used. The synthetic resin-containing composition may also be referred to as a size liquor or synthetic resin liquor.

The impregnation of the impregnate in the process according to the invention is preferably from 90% to 130%, preferably from 100% to 120%, more preferably from 105% to 115%. In particular, the ratio of the amount of the composition containing a synthetic resin which has taken up the paper to be impregnated can be understood to mean the weight of the paper to be impregnated. The curing can be carried out by a person skilled in the art, e.g. determine by simple weighing.

In the process according to the invention, the resination for producing the impregnates is advantageously achieved by immersing the relevant layer, for example a base paper, in a bath containing the composition containing a synthetic resin. In this way, the layer can be saturated with the composition containing a synthetic resin. Any excess of the composition can be removed by means of rollers or wipers.

Subsequently, the impregnate can be dried in a heating channel. The drying can be carried out in particular by a hot air stream. The hot air flow may have a temperature of 130 ° C to 200 ° C.

In the process of the invention, the laminate may preferably be obtained by hot pressing in a short-cycle press. In a further embodiment of the method according to the invention, the laminate can be obtained by hot pressing in a multi-daylight press.

Following the hot pressing, the obtained laminate can be further processed in the process according to the invention in particular. For example, protruding material can be removed. In addition, the edges of the resulting laminate can be adjusted. Finally, with single-sided laminates, the backside can be sanded.

In the process of the present invention, the synthetic resin-containing composition and the acid-releasing curing agent for the synthetic resin may be combined in different manners.

According to one embodiment of the method according to the invention, the acid-releasing hardener is contained in the composition containing a synthetic resin. As a result, a good mixing of synthetic resin and acid-releasing hardener is achieved.

According to a further embodiment of the method according to the invention, the acid-releasing hardener is applied in an additional step to the impregnated base paper. Alternatively, the acid-releasing curing agent can also be applied to the carrier layer in an additional step. Furthermore, the acid-releasing hardener can be applied in particular to the base paper and to the carrier layer. Preferably, the acid-releasing curing agent is applied to the impregnated base paper and / or to the carrier layer before the Stratification in step b. provided. Further, the acid-releasing hardener may be applied to the layer to which the base paper is applied.

The process according to the invention can be used in particular for the production of single-sidedly bonded laminates. The process according to the invention can also be used for the production of double-sidedly bonded laminates.

Furthermore, the invention relates to laminates which have been produced by a process according to the invention.

In addition, the invention relates to the use of a hardener for synthetic resins, which forms at least one acid by hydrolysis, in a process for producing laminates comprising a support layer having a water vapor diffusion resistance number of at least 250 according to DIN EN ISO 12572.

In this case, the features of the use according to the invention that apply above to the features of the method according to the invention apply accordingly.

In particular, in a preferred embodiment of the use according to the invention, the carrier layer has a water vapor diffusion resistance number according to DIN EN ISO 12572 testing of at least 500, in particular at least 1000. Further preferably, the carrier layer in the use according to the invention has a water vapor diffusion resistance number according to testing according to DIN EN ISO 12572 of at least 2000.

Advantageously, the laminate in the use according to the invention contains a compact plate.

In one embodiment of the use according to the invention, the acid-releasing hardener contains an acid anhydride. In a further embodiment of the use according to the invention, the acid-releasing hardener contains a lactone. In In another embodiment of the use according to the invention, the acid-releasing hardener contains an acid anhydride and a lactone.

Advantageously, the synthetic resin in the use according to the invention is an aminoplast resin.

In a preferred embodiment of the use according to the invention, the process is the above-described inventive process.

The principle of the invention will be explained in more detail below using an example.

Example: The following chemicals were used:

Melamine resin (Prefere 700690L, MetaDynea); Hardener melamine (Madurit MH 836, Ineos); Wetting agent (Hypersal XT 782, Ineos); Release agents (Madurit ™ 3759, Ineos); Plasticizer (Plextol BV411, Synthomer); Gamma-butyrolactone (INCHEM Chemie Handel GmbH).

To prepare an impregnate, an aminoplast resin liquor having the following composition was prepared: Table 1: Composition Aminoplastharzflotte substance % By weight melamine resin 80.5 water 12.0 Hardener melamine 0.5 Wetting, separating and plasticizing agents 5.0 gamma-butyrolactone 2.0

The solid resin content was 48.4%, the viscosity at 20 ° C 19.24 mPas and the clouding time 210 seconds.

The base paper used was an underlay paper with a base paper grammage of 150 g / m ² . The aminoplast resin liquor was placed in an impregnation trough and the base paper was soaked by pulling the base paper through this trough. Subsequently, the impregnate thus obtained was dried. The dried impregnate had a impregnation weight of 335 g / m ² , a residual moisture content of about 6% and a caustic content of about 110%.

Subsequently, the impregnate was applied to a compact plate with a thickness of 4.8 mm. A decorative paper was applied to the layering thus obtained. The coating thus obtained, consisting of carrier layer, impregnate and decorative paper was pressed at a pressing pressure of 45 kg / cm ² , a pressing temperature of 180 ° C with a pressing time of 80 seconds. There was no blistering on the surface of the resulting coated compact plate.

Claims (26)

A process for producing a laminate comprising at least one carrier layer and a further layer, comprising: a. Making an impregnate by soaking a base paper with a composition containing a synthetic resin, b. Providing a lamination comprising a carrier layer and an impregnate by applying the impregnate to the carrier layer, and c. Hot pressing of the provided stratification, characterized in that a curing agent is used for the synthetic resin, which releases at least one acid by hydrolysis during hot pressing, and the carrier layer has a water vapor diffusion resistance coefficient according to testing according to DIN EN ISO 12572 of at least 250. A method according to claim 1, characterized in that the release of the acid contributes to the curing of the synthetic resin. Method according to one of the preceding claims, characterized in that the curing agent releases at least one acid in the presence of water and / or under the action of heat. Method according to one of the preceding claims, characterized in that the released during hot pressing at least one acid is formed by reaction of the hardener with water vapor. Method according to one of the preceding claims, characterized in that the pressing time during hot pressing less than 120 seconds, in particular less than 90 seconds. Method according to one of the preceding claims, characterized in that the hot pressing at a temperature of 110 ° C to 200 ° C, in particular from 120 ° C to 190 ° C or from 130 ° C to 180 ° C is performed. Method according to one of the preceding claims, characterized in that the hot pressing at a pressure of 1 to 90 bar, in particular from 10 to 80 or 20 to 70 bar, is performed. Method according to one of the preceding claims, characterized in that the amount of acid-releasing curing agent 0.5 to 30 wt.%, In particular 0.5 to 20 wt.%, Based on the total mass of resin and hardener is. Method according to one of the preceding claims, characterized in that the liberated acid has a molecular weight of 40 g / mol to 500 g / mol, in particular from 40 g / mol to 300 g / mol. Method according to one of the preceding claims, characterized in that the liberated by the hardener at least one acid is a Brönsted acid having a pKa of less than 8, in particular less than 7, is. Method according to one of the preceding claims, characterized in that a hardener is used as the acid-releasing hardener, which contains an acid anhydride and / or an ester, in particular a lactone. A method according to claim 11, characterized in that the lactone is gamma-butyrolactone and / or epsilon-caprolactone. A method according to claim 11 or 12, characterized in that the acid anhydride is selected from the group consisting of acetic anhydride, maleic anhydride, succinic anhydride and dilactide. Method according to one of the preceding claims, characterized in that the synthetic resin is an aminoplast resin. Method according to one of the preceding claims, characterized in that the base paper is an underlay paper. Method according to one of the preceding claims, characterized in that in an additional step after step b. to the ones in step b. provided layering additionally decorative paper and / or a cover layer, in particular an overlay paper is applied. Method according to one of the preceding claims, characterized in that the carrier layer comprises a compact disk. Method according to one of claims 1 to 16, characterized in that the carrier layer comprises one or more Natronkraftpapiere which have been impregnated with a synthetic resin selected from the group consisting of melamine-formaldehyde resin, urea-formaldehyde resin, phenol-formaldehyde resin and mixtures thereof. A method according to any one of the preceding claims, characterized in that the acid-releasing hardener is contained in the composition containing a synthetic resin. Method according to one of the preceding claims, characterized in that the acid-releasing hardener in an additional step on the impregnated base paper and / or applied to the carrier layer. Laminate obtainable by a process according to one of claims 1 to 20. Use of a hardener for synthetic resins, which forms at least one acid by hydrolysis, in a process for the production of laminates comprising a support layer having a water vapor diffusion resistance number according to DIN EN ISO 12572 testing of at least 250. Use according to claim 22, characterized in that the laminate contains a compact plate. Use according to one of claims 22 or 23, characterized in that the acid-releasing hardener contains an acid anhydride and / or a lactone. Use according to any one of claims 22 to 24, characterized in that the synthetic resin is an aminoplast resin. Use according to any one of claims 22 to 25, characterized in that the method is a method according to any one of claims 1 to 20.